To learn more about how the brain processes spatial information, researchers at the Shimegi Lab at Osaka University in Japan focus on a neuromodulator named noradrenaline. Neuromodulators function to moderate the effects of neurotransmitters in the brain. Noradrenaline is secreted in the brain to regulate heart rate, blood flow, the visual system, and other body functions depending on the behavioral context and physiological states of an animal, including humans. Drugs called beta blockers, target its effects.
In a new set of experiments, the researchers observed the effects of noradrenaline on the vision of free-moving rats. They measured the rats’ contrast sensitivity, which refers to their ability to distinguish objects at different light and dark contrasts. To view the vision effects of noradrenaline, the researchers suppress its effect on contrast sensitivity for a specific range of spatial frequencies using propranolol hydrochloride, a beta-blocker used to treat tremors, angina (chest pain), hypertension (high blood pressure), heart rhythm disorders, and other heart or circulatory conditions. The scientists conclude that noradrenaline could improve vision by targeting a very small subgroup of neurons or neural circuits in the brain.